JPH10282013A - Defect inspection of surface of disc, direction of grinding recognition device and method of using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the detecting accuracy of a defect by providing a direction of grinding recognizing part or the like which recognizes the direction of grinding of a disc depending on changes in the output of a photodetecting part to inhibit changes in image data when the direction of grinding changes. SOLUTION: A first light emitting section 2 illuminates light onto the surface of a disc 10 held by a first disc holding part 1 and a first photodetecting section 3 receives the reflected light from the surface of the disc 10. A first moving mechanism 4 changes the relative positional relationship between a system containing the light emitting section 2 and the photodetecting section 3 and the disc 10 so that the angle of emission in the horizontal direction continuously varies between the emitted light and the direction of grinding of the disc 10. The direction of grinding recognizing section 5 recognizes the direction of grinding of the disc 10 depending on changes in the output of the photodetecting section 3. A lighting apparatus illuminates the surface of the disc 10 only within a specified range of an angle of emission in the horizontal direction between the second emitted light and the direction of grinding. A second moving mechanism alters a relative positional relationship so that the surface of the disc 10 is scanned over the entire range of inspection by a second photodetecting section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for inspecting a surface of an aluminum magnetic disk or the like for defects.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 4-276664 and Japanese Patent Application Laid-Open No.
No. 9049 is disclosed. JP-A-4-276
Japanese Patent No. 641 employs a bright field method in which a light receiving portion receives specularly reflected light of light applied to the surface of an aluminum magnetic disk substrate. That is, the image of the substrate surface is captured by receiving the specularly reflected light by the imaging device, and the presence or absence of a surface defect is detected from the density of the obtained image. Japanese Patent Application Laid-Open No. 62-269049 discloses a dark field method in which a light receiving portion is provided at a position that does not receive specularly reflected light of light applied to the surface of a disk substrate and receives only irregularly reflected light due to defects. .

[0003] On the other hand, the image processing system removes the influence of a change in the angle between the polishing direction of the disk and the emitted light on the output value of the light receiving section. J78-D-II, no. 4, 597 ~ 60
There are seven pages.

[0004]

The surface of an aluminum magnetic disk is polished in a certain direction.
If the angle formed by the disc polishing direction and the emitted light projected on the disc surface is different, the light reflection mode is different. However, Japanese Patent Application Laid-Open No. 4-2766641, Japanese Patent Application Laid-Open No. 62-26904
Japanese Patent Application Laid-Open No. 9-205509 inspects a disk without considering the change in the disk polishing direction and the angle of the emitted light projected on the disk surface. Therefore, with the change of the angle, the image data of the polished surface changes by about several tens of percent when the bright field method is used, and when the dark field method is used, the angle between the polished surface and the emitted light is around 90 degrees. However, there is a problem that the defect detection accuracy is reduced because a large change occurs. In addition, the technology of the IEICE Transactions has a problem that the image processing cannot be performed unless the angle of the flaw is known, so that the automatic inspection cannot be performed.

As described above, an automatic inspection apparatus and method which recognize the polishing direction in advance and suppress the fluctuation of the image data when the polishing direction changes, and which have excellent defect detection accuracy have not been provided. Also, no apparatus or method for detecting the polishing direction of the disk is provided.

[0006]

The gist of the present invention is to provide a first disk holding unit 1, a first light emitting unit 2 for emitting light to a disk surface, and a first light emitting unit 2 for receiving light reflected from the disk surface. A light receiving unit 3 and a system including the first light emitting unit 2 and the first light receiving unit 3 so that the horizontal emission angle formed by the first emission light and the polishing direction of the disc continuously changes. A first moving mechanism 4 for changing the relative positional relationship with the disk, a polishing direction recognition unit 5 for recognizing a polishing direction of the disk based on a change in the output of the first light receiving unit 3, and a second disk holding unit 11
And, the irradiation direction of the light so as to irradiate only a light having one or more second light emitting portions 12 and having a horizontal emission angle between the emitted light and the polishing direction within a predetermined range on the disk surface. The illumination device 15 that changes relatively, at least one second light receiving unit 13 that receives reflected light from the disk surface, and the second light receiving unit 13 scans the entire inspection area on the disk surface. A second moving mechanism 14 for changing the relative positional relationship between the second light receiving unit 13 and the disk; and an image processing unit 16 for processing a signal from the second light receiving unit 13.
Is a disk surface defect inspection apparatus having the following.

Further, the gist of the present invention is to provide a polishing direction recognizing means 7 for recognizing a polishing direction of a disk surface, a second disk holding portion 11, and one or more second light emitting portions 12 for emitting light. Illuminating device 15 that irradiates light to the disk surface while relatively changing the direction of light irradiation so that the horizontal direction emission angle between the polishing direction and the polishing direction irradiates only light within a predetermined range.
And at least one second light receiving unit 13 for receiving the reflected light from the disk surface; and the illuminating device 15 and the second light receiving unit 13 so that the inspection range on the disk surface is completely scanned by the second light receiving unit 13. A second moving mechanism 14 for changing the relative positional relationship between the system including the light receiving unit 13 and the disk;
An image processing unit 16 for processing a signal from the second light receiving unit 13 is a disk surface defect inspection apparatus.

Further, the gist of the present invention is that, after recognizing the polishing direction of the disk surface using the disk surface defect inspection apparatus, the illumination device sets the horizontal output angle between the output light and the polishing direction within a predetermined range. This is a method of irradiating the disk surface with light to inspect the disk surface for defects.

The gist of the present invention is to provide a first disk holding unit 1, at least one first light emitting unit 2 for emitting light to a disk surface, and a first light receiving unit 2 for receiving reflected light from the disk surface. A first light receiving portion 3 paired with the first light emitting portion, and a first light emitting portion 2 and a first light receiving portion such that a horizontal emitting angle between the emitted light and the polishing direction of the disk continuously changes. It has a first moving mechanism 4 for changing the relative positional relationship between the system including the unit 3 and the disk, and a polishing direction recognition unit 5 for recognizing the polishing direction of the disk from a change in the output of the first light receiving unit 3. This is a polishing direction recognition device.

Further, the gist of the present invention is a polishing direction recognition method using the polishing direction recognition device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.
In the present invention, the light emitting unit used for recognition of the polishing direction, the light receiving unit, and the moving mechanism are referred to as “first light emitting unit”, respectively.
"First light receiving unit", referred to as "first moving mechanism", the light emitting unit used for defect detection, the light receiving unit, the moving mechanism for "second light emitting unit", "second light receiving unit", respectively This is referred to as a “second movement mechanism”. Lights emitted from the first light emitting portion and the second light emitting portion are referred to as “first emitted light” and “second emitted light”, respectively.

FIG. 1 is a diagram showing an example of the positional relationship of each part used in the step of recognizing the polishing direction on a plane passing through the first light emitting part and the first light receiving part and perpendicular to the disk surface. . As shown in FIG. 1, in the following description, a perpendicular line at the intersection of the light emitted from the first light emitting portion and the disk surface,
The angle formed by the emission direction is referred to as “first emission angle a ₁ ”, and the angle formed by this perpendicular and the light receiving direction of the first light receiving portion is referred to as “first light receiving angle b”.
₁ ".

FIG. 5 is a diagram showing an example of the positional relationship of the respective parts used in the step of inspecting the disk for defects on a plane passing through the second light emitting part and the second light receiving part and perpendicular to the disk surface. . As shown in FIG. 5, in the following description, an angle between a perpendicular line at the intersection of the light emitted from the second light emitting unit and the disk surface and the emission direction is referred to as a “second emission angle a ₂ ” The angle formed by the light receiving directions is referred to as “second light receiving angle b ₂ ”. Further, in the present invention, the “point sensor” indicates only the light receiving portion.

First, the relationship between the light emitting direction and the disk polishing direction will be described with reference to the drawings. FIG. 2 is a diagram for explaining the relationship between the arrangement of the first light emitting unit and the first light receiving unit and the reflection pattern. FIG. 3 illustrates a state in which the first light emitting unit 2 and the first light receiving unit 3 are arranged above one radius of the disk 10 and the disk is viewed from above the disk 10 in the vertical direction. In order to show a case where the relative positional relationship between the system including the first light emitting unit 2 and the first light receiving unit 3 and the polishing direction of the disc is different, three pairs of the first light emitting unit and The first light receiving unit is illustrated, and the respective arrangement states are indicated as x, y, and z.

In this case, the three pairs of the first light emitting portion and the first light receiving portion are arranged vertically above the disk radius in any of the x, y, and z arrangement states. FIG.
In the above, the polishing direction of the disk 10 is the left-right direction on the paper surface.

The first outgoing angle a ₁ is 30 degrees, the first light receiving angle b ₁ is 0 degrees, and the first outgoing light illuminates a range including immediately below the first light receiving section 3. In addition, a lens is arranged at the tip of the first light receiving unit 3 to make it easy to receive the reflection pattern 6. Note that the “reflection pattern” is an illustration of the area on the disk surface where light reflected in the direction perpendicular to the disk surface exists. The reflection pattern 6 also
Arrangement state x, y, z of first light emitting unit and first light receiving unit
3 are shown corresponding to each of FIG.

In general, when light is applied to a polished disk surface, the angle between the emitted light projected on the disk surface and the polishing direction (hereinafter, such an angle is referred to as a "horizontal emission angle") is approximately 90 degrees. Sometimes, light is reflected in a direction perpendicular to the disk surface. The first outgoing light irradiates a certain area on the disk surface. For this reason, the irradiation range of light having a horizontal emission angle of about 90 degrees in the irradiation range on the disk surface appears as a reflection pattern.

Therefore, at this time, the longitudinal direction of the reflection pattern 6 of the light emitted from the first light emitting portion 2 on the disk 10 is always about 90 degrees with respect to the polishing direction. Therefore, when the angle between the straight line connecting the first light emitting portion and the first light receiving portion and the polishing direction is 90 degrees, as in the reflection pattern in the arrangement state of z in FIG. Is the maximum.

FIG. 3 shows the angle between the polishing direction of the disk in FIG. 2 and the first emission light projected on the disk surface (hereinafter referred to as "first projection emission light"). This angle in the device to be used is referred to as “horizontal emission angle c ₁ ”
FIG. 7 is a diagram showing the relationship between the output of the light receiving unit. The output of the light receiving unit is obtained by subjecting a signal from the light receiving unit to 8-bit A / D conversion. The output of the light receiving portion, in this case the horizontal emission angle c ₁ is 90 degrees ± 20 degrees, and are changing rapidly at the position of 270 degrees ± 20 degrees. Thus in the horizontal emission angle c ₁ change affects the reflection pattern of light, greatly change the output of the light receiving portion.

In order to recognize the polishing direction of the disk, the reflected light is read by the first light receiving portion while the horizontal emission angle c ₁ is continuously changed, and the change in the output is detected. Rising (in this case 70 degrees or 25 degrees)
0 degree) or falling (in this case, 110 degrees or 290 degrees).

Here, the case where the first light emitting portion and the first light receiving portion are arranged so that the first light receiving portion does not receive the specular reflected light of the first outgoing light has been described as an example. in the case where the regularly reflected light is disposed a first light emitting portion and the first light receiving unit to receive well, changing the horizontal emission angle c ₁ continuously, the angle of the output of the light receiving portion changes abruptly There is. The output change is relatively small when the output level is high or low between these angles. Therefore, by similarly checking the rise or fall of the output of the light receiving section, the polishing direction of the disk can be recognized. However, in this case, the change in the output is smaller than in the above-described case, and the horizontal emission angle c _{1 at} which the output rises and falls differs.

On the other hand, the relationship between the horizontal emission angle and the output of the light receiving section as described above can be applied to defect detection. When the dark field method is used in the defect detection, an angle formed between the polishing direction of the disk and the second emission light projected on the disk surface (hereinafter, referred to as “second projected emission light”) (hereinafter, this angle in the defect detection step). Is referred to as the “horizontal emission angle c ₂ ”) and the output of the light receiving section has the same relationship as in the case of recognizing the polishing direction. That is, when you change the horizontal emission angle c ₂ continuously outputs of the light receiving portion changes rapidly at a particular angle, a relatively small amount of change in the output in a high state or a low state output level therebetween . For example, by setting the second light emitting portion and the second light-receiving portion of the arrangement relationship as in the case of the polishing direction recognition, relationship between the output of the light receiving portion and the horizontal emission angle c ₂ is similar to FIG 3 .

Accordingly, when the dark-field method is used, the output of the light receiving section is in a range where the output is low (in the example of FIG. 3, the horizontal emission angle c ₂ is 0 to 70 degrees, 110 to 250 degrees, 290).
By irradiating light (so that the angle is between
Since the output of the light receiving unit is always stabilized at a low level, stable image data can be obtained.

When the bright field method is used, light in a range where the output of the light receiving section is high is irradiated. However, in the same manner as in the case of recognizing the polishing direction, the horizontal emission angle c _{2 at which} the output of the second light receiving unit in the bright field method causes a rise and a fall occurs.
Is different from that in the dark field method. Thus the scope of the horizontal emission angle c ₂ irradiating the case light is different from that of the dark field method.

In the present invention, as described above, 1) the polishing direction of the disk is recognized, and 2) the range of the horizontal emission angle is set to a range where the output of the light receiving section is small, that is, the change of the image data is small. Inspection is performed in a state set in the range. In the apparatus of the present invention, the step of recognizing the polishing direction of the disk and the step of inspecting for defects can be performed by another apparatus, or can be performed by one apparatus.

Hereinafter, each part of the apparatus will be described in more detail. The disc is usually placed horizontally with its polished surface facing up. Here, for the sake of convenience, the positional relationship between the components of the apparatus will be described based on this state. Incidentally, the method of placing the disk is not limited to this.

In the step of recognizing the polishing direction, the disk is held by the first disk holder. Hereinafter, a description will be given of a state where the disk is held by the first disk holding unit.

The first light emitting portion and the first light receiving portion are provided above the polished disk surface. If both sides of the disk are polished, the first light emitting part and the first light receiving part can be installed below the disk surface by holding the disk without any obstacles below the disk. is there.

In order to make the whole apparatus simpler,
It is preferable that the first light emitting portion and the first light receiving portion are installed so as to form a pair vertically above or below the disk diameter. As described above, the first light emitting unit and the first light receiving unit are:
It is conceivable to arrange so as not to receive the regular reflection light from the first light emitting unit or to arrange so as to receive the regular reflection light.
At an angle at which the output of the light receiving portion rapidly changes, the former arrangement state in which the change amount is large is desirable.

The first light emitting portion is desirably a relatively small point light source for accurately controlling the light emitting angle, such as an optical fiber light guide. The irradiation range of the first light emitting unit is determined based on the position of the first light receiving unit, the reading range, and the like. Further, the first light emitting portion is arranged so as to pass through a surface perpendicular to the disk surface including the first light receiving portion, and the first light emitting portion irradiates an area on the disk surface read by the first light receiving portion. I do. Although the first output angle a ₁ is not particularly limited, it is preferably in the range of 30 to 60 degrees.

The first light receiving portion preferably detects a light in as narrow a range as possible, for example, a point sensor in order to accurately recognize the polishing direction. Although the first light-receiving angle b ₁ is not particularly limited, when not receiving the regular reflection light arrangement from the first light emitting portion is preferably approximately 0 degrees. In the case of a configuration that receives specularly reflected light, the first light receiving angle b ₁
Is set equal to the first emission angle a ₁ . In order to receive the reflected light effectively, it is desirable to arrange a lens at the tip of the first light receiving unit.

The output of the light receiving section is input to the polishing direction recognizing section. The polishing direction recognition unit recognizes the polishing direction based on a change in the output of the light receiving unit. Various information processing devices and the like are used for the polishing direction recognition unit. It is preferable to use a simple sequencer or the like as the information processing device in order to simplify the device.

As described with reference to FIGS. 2 and 3, the polishing direction recognition unit recognizes the polishing direction when the output of the light receiving unit changes greatly. Note 2, the horizontal emission angle c ₁ in the case of FIG. 3 is 90 degrees ± 20 degrees, and, the output at 270 ° ± 20 ° abruptly changes, the output of the first light receiving portion rapidly changes horizontal emission angle c ₁ varies depending on various conditions of the size, position setting of the first light emitting portion and the first light receiving portion and the like of the light emitting range used.

Therefore, when recognizing the polishing direction, the angle between the first projection output light and the polishing direction of the disk changes continuously, and the first output light irradiates the disk surface. The relative positional relationship between the system including the first light emitting unit and the first light receiving unit and the disk is moved using the first moving mechanism. As the first moving mechanism, for example, a disk or a system including a first light emitting portion and a first light receiving portion is defined by a perpendicular to a disk surface passing through the center of the disk (hereinafter, referred to as “central axis of the disk”). One that rotates as a rotation axis is given. In order to easily configure the apparatus, a mechanism for rotating a disk is preferable.

In order for the polishing direction recognizing unit to determine the rise and fall of the output of the light receiving unit more simply, a certain threshold is set.
Alternatively, it is desirable to adopt a method of determining rising or falling when the output changes from the above to the following. In the case of using this method, the output value of the light receiving unit differs depending on various conditions such as the amount of emitted light, and the threshold value is set as needed according to the situation. Rising and falling,
Alternatively, it is desirable to set the value to a value large enough that the polishing direction is not erroneously recognized due to a small change in the output between the fall and the rise. For example using disk samples, setting the threshold to 3 times the value of the minimum value of the output of the light receiving portion when the have a horizontal emission angle c ₁ is varied from 0 to 360 degrees.

Since the output of the light receiving section also changes depending on the disc defect, the polishing direction may be erroneously recognized due to the disc defect depending on the set value of the threshold value. However, even if a threshold value is set for such a value, the disk having such a defect is judged to be defective in the process of inspecting the defect on the disk surface, which does not affect excessive detection and oversight of the defect. No problem occurs.
Further, the movement may be continuous or intermittent.

In order to effectively recognize the polishing direction, it is preferable that the polishing direction recognizing means is composed of the above-described components, but the polishing direction recognizing means of the present invention is not necessarily limited to this. .

In the step of inspecting the disk surface for defects, the disk is held by a second disk holding unit. Hereinafter, a description will be given of a state where the disk is held by the second disk holding unit. Further, when the first moving mechanism and the second moving mechanism are used as described later, the first disk holding unit and the second disk holding unit can also be used.

The second light emitting section and the second light receiving section are installed above the polished disk surface. If both sides of the disk are polished, the second light emitting part and the second light receiving part can be installed below the disk surface if the disk is held without any obstacle below the disk. is there.

The second emission angle a of the emitted light emitted from the illumination device
₂ is not particularly limited. Practically, the angle is preferably in the range of 30 degrees to 60 degrees. When it is intended to irradiate a wide area on the disk surface, it is preferable to consider that other devices do not hinder the emitted light, It is more preferable to set the degree.

The illumination device of the present invention has a horizontal emission angle c _2.
Works so that only the outgoing light within the “predetermined range” irradiates the disk surface. Can be used various kinds of information processing apparatus to control the horizontal emission angle c _2, it can also be used as a more convenient sequencer. An optimal control method is adopted according to the configuration of the entire defect inspection apparatus.

For example, by providing a plurality of pairs of the first light emitting portion and the first light receiving portion as described above, the polishing direction is recognized each time, and the horizontal emission angle c ₂ is controlled based on the polishing direction recognition result. Is also possible. However, for accurate control, a large number of first light emitting units and first light receiving units are required. If the number is reduced, the control of the light irradiation direction lacks accuracy. Therefore, for example, after once recognizing the polishing direction, only a system including the illuminating device and the second light receiving unit, and only the emission light such that the horizontal emission angle c ₂ is within a predetermined range from the relative movement amount with respect to the disk It is desirable to control the lighting device so that the light illuminates the disk surface. Note that the control device of the lighting device and the polishing direction recognition unit do not necessarily need to be clearly separated as devices, and these processes can be performed by one device.

By irradiating the disk surface while continuously changing the horizontal emission angle c ₂ , and measuring the output of the second light receiving portion, the output of the second light receiving portion is measured in the same principle as in the case of recognizing the polishing direction. The output also shows a large change at a certain angle. As described above, the mode of the output change of the second light receiving unit differs depending on whether or not the second light receiving unit receives the regular reflection light of the light from the lighting device.

Here, the "predetermined range" is between the fall and rise of the output or between the rise and fall of the output, and the output angle c in the horizontal direction where the amount of change in the output is relatively small.
_In the range of ₂ , the output level is either a low range or a high range. Note that the horizontal emission angle c ₂ when the output of the light receiving section rises or falls is determined by the defect detection method used, the size of the light emitting range, and the position setting of the second light emitting section and the second light receiving section. The predetermined range is determined in view of these conditions. As the “predetermined range”, the range in which the output change amount is relatively small among the ranges in which the output level is low or the range in which the output level is high is selected.
It is determined by which of the dark-field methods is adopted.

When the dark field method is used, a range where the output level of the second light receiving section is low is selected as the "predetermined range". That is, the illumination device illuminates only from the position where the level of the amount of light received by the second light receiving unit indicates a low value. For example the second output angle a ₂ is set to about 30 to 60 degrees, if you set the second acceptance angle b ₂ to about 0 degrees, the horizontal emission angle c ₂ 0 to 70 degrees,
It is desirable to design the lighting device to be 110 to 250 degrees, 290 to 360 degrees. More desirably, the angles are 0 to 60 degrees, 120 to 240 degrees, and 280 to 360 degrees. When the bright field method is used, a range in which the output level of the second light receiving unit is high is selected as the “predetermined range”. That is, the illuminating device irradiates the disk surface only from the position where the level of the amount of light received by the second light receiving unit has a high value. In the present invention, either the bright-field method or the dark-field method can be used, but the dark-field method is preferable because finer defects can be detected.

Such an illuminating device has a plurality of second light emitting portions for emitting light having various horizontal emission angles c _2, and emits light whose horizontal emission angle c ₂ is within a predetermined range. A structure in which only the emission section that emits light is turned on, a structure in which the horizontal emission angle c ₂ is configured to block light from the emission section that emits light outside a predetermined range by a light shielding device, and a structure in which the horizontal emission angle c ₂ is An example is a structure in which an emission unit moves to a position where light is emitted within a predetermined range. Of these, those having a light-shielding portion are preferable because of their simple structure. Further, in order to irradiate light so as to cover the inspection area on the disk surface more uniformly, a plurality of second light emitting parts are installed concentrically with the center at the center of the inspection area. Is preferred.

For example, two points on one diameter of the disk and two points (for example, O ₁ and O _{2 in} FIG. 6) which are the midpoints of the outer diameter and the inner diameter of the disk are centered. A plurality of second light emitting portions are arranged above the concentric circles at a fixed angle interval with respect to a vertical axis (central axis) passing through O ₁ and O ₂ , and these respective central axes are set as axes. A rotatable light-shielding part is arranged, and the horizontal emission angle C ₂
Has a structure that shields the second outgoing light that is out of the predetermined range. In addition, a light-shielding part that can be opened and closed is attached to the tip of each second emission part, and these are turned on and off by solenoids.
It is also possible to adopt a structure of opening and closing by FF. In this case, the finer adjustment of the emission angle becomes possible as the number of the second emission portions increases, but if the number is too large, the structure becomes complicated.
It is preferable that the concentric circles are installed so as to have an interval of about 30 degrees and a total angle of about 180 degrees with respect to the central axis.

Various sensors such as a point sensor and a line sensor can be used as the second light receiving section. When a sensor that receives light in only a narrow range is used, a complicated device is required to inspect the entire disk surface. Therefore, a line sensor, an area sensor, and the like are preferable. When a dark-field method is used as the defect inspection method, if a sensor that detects a very wide range is used, reflected light of a normal portion may be received. Therefore, it is preferable to use a point sensor, a line sensor, or the like. . In this case, a line sensor is more preferable in order to easily configure the apparatus. Although the second acceptance angle b ₂ is not particularly limited, when using the dark field method as a defect detection method, is preferably approximately 0 degrees. When using the bright field method set to approximately the same angle as the second output angle a _2.

In a certain inspection state, if the reading range of the second light receiving unit does not cover the entire inspection range of the disk surface, the inspection of the disk surface is performed to inspect the entire inspection range of the disk surface. A second moving mechanism for relatively moving the disk and the range read by the second light receiving unit so as to scan the entire inspection range is arranged. The inspection range can be set on the entire surface of the disk and can be inspected at once. For example, the inspection surface can be set by dividing the disk surface into halves and the inspection can be performed twice. In this case 2
The inspection can be performed by another device. When the reading range of the second light receiving unit covers the entire inspection range on the disk surface, the second moving mechanism is unnecessary. In this case, the lighting device is fixed so as to irradiate the disk from an angle within a predetermined range.

In order to easily change the light emitting direction of the illuminating device, a device in which the polishing direction is continuously changed, for example, a rotating device for rotating the disk around the center axis of the disk is preferable. . If the first moving mechanism and the second moving mechanism have the same moving mode, both can be used as well.

Known image processing apparatuses can be used.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an apparatus for recognizing the polishing direction of a disk will be described with reference to FIG. The disks to be inspected were 3.5 inch aluminum magnetic disks. The size is an outer diameter of 95 mm and an inner diameter of 25 mm. Although the polishing direction is not fixed, it was polished in one direction.

The first light emitting portion 2 and the first light receiving portion 3 are respectively installed one above the radius of the disk in the vertical direction, the first light emitting angle a ₁ is about 30 degrees, and the first light receiving angle b ₁ was approximately 0 degrees, and the first light emitting portion 2 illuminated directly below the first light receiving portion 3. The distance between the first light emitting unit 2 and the disk and the distance between the first light receiving unit 3 and the disk are each 13
mm. First light emitting unit 2 and first light receiving unit 3
The fiber sensor FX4 manufactured by SUNX was used. A lens was used at the tip of the first light receiving unit 3 to make it easy to receive the reflection pattern.

As the first moving mechanism 4, a rotating mechanism for rotating the disk around the center of the disk as a rotation axis was used. The first disk holding unit was installed so as to interlock with this rotation mechanism. The disk was set on the first disk holder. In this state, the light is emitted from the first light emitting portion while rotating the disk at a speed of 5 seconds / time, the reflected light is received by the first light receiving portion, and the output of the first light receiving portion is polished in the polishing direction. It was sent to the recognition unit 5. A sequencer was used as the polishing direction recognition unit 5. In the sequencer, the threshold value is set to a value three times the minimum value of the output of the first light receiving unit, and when the output value changes from a value lower than the threshold value to a value higher than the threshold value, the rise is detected and the rotation of the disk is stopped.

Next, the configuration of the apparatus in the defect inspection process will be described. The outline of the apparatus will be described with reference to FIGS. 4, 5 and 6 as appropriate. As the second moving mechanism 14, a rotating mechanism that rotates the disk about a perpendicular to the disk surface passing through the center of the disk as a rotation axis was used. As described above, the disk 10 whose polishing direction was set to a fixed direction was set on the second disk holding unit 11 interlocked with the rotation mechanism. 5 in this state
The inspection was performed while rotating at a speed of seconds / times. The disks were rotated at least half a turn per inspection of the disks. The transport system 19 includes the second disk holding unit, the rotating mechanism, a disk transport device, and a device for sorting non-defective products and defective products. The transport system 19 was controlled from the host computer 17 through the control unit 18.

As the second light emitting portion 12, an optical fiber light guide (model name: GB4-2000) manufactured by Mitsubishi Rayon Co., Ltd.
Were used. Each of the light guides has a tip branched into two, and a condenser lens is attached to each tip.

Referring to FIG. 6, the lighting device and the second light receiving portion 13 will be described.
The arrangement of a line sensor used as a device will be described in more detail.

FIG. 6 shows the arrangement of the illuminating devices and the line sensors when the disk is viewed from above in the vertical direction. The disk 10 rotates around the center O of the disk. The reading ranges 61 and 62 on the disk surface of the line sensor are set on one diameter of the disk. The line sensor is installed vertically above these reading ranges 61 and 62. For this reason, by rotating the disk 10 by half, the entire surface of the disk could be inspected.

The tips of the light guides are shown as 41 to 46 and 51 to 56. In this light guide, the emitted light has various horizontal emission angles, and the reading range 6
Plural units were installed so as to illuminate 1, 62. Emission part 41
-46 is an upper concentric circles around the O _1, O ₁
Are arranged so as to be at an interval of about 30 degrees. Similarly, the emission unit 51 to 56, a upper concentric circles centered on O _2, was arranged to be about 30 degree intervals with respect to O _2. O ₁ and O ₂ are points on the diameter where 61 and 62 are located, and are the midpoints between the inner diameter and the outer diameter.

Light-shielding portions 31 and 32 are provided to block a second emission portion that emits light having an emission angle c _{2 in the} horizontal direction exceeding ± 70 degrees with respect to the polishing direction of the rotating disk 10. The light-shielding portions 31 and 32 are structured to rotate around perpendiculars passing through O ₁ and O ₂ , respectively, and to block light whose horizontal emission angle c ₂ exceeds ± 70 degrees as the polishing direction changes. Was controlled by a sequencer to rotate.

The second emission angles a ₂ of the emission sections 41 to 46 and 51 to 56 were all about 45 degrees, and the second light reception angle b ₂ of the line sensor was about 0 degrees. For this reason,
The line sensor hardly received the reflected light on the normal polished surface, and received the scattered reflected light if the disk 10 had a defect. As the light source 20, a light source device (model name: ELI-100J) manufactured by Mitsubishi Rayon Co., Ltd. was used.

A line sensor was used as the second light receiving section 13 to receive the reflected light from the disk 10. As a line sensor, a line CCD camera (model name: SCD-5000-20) manufactured by Mitsubishi Rayon Co., Ltd. was used. The number of elements of the line sensor is 5000, the reading range in the longitudinal direction of the line sensor with respect to a plane including the disk is 150 mm, and one line sensor covers a range of one disk with a diameter of 95 mm. The resolution in the element direction is 30 μm / element.
A lens for effectively receiving the reflected light from the disk was disposed at the tip of the line sensor. A macro lens (f = 50 mm) was used as the lens. The distance between the disc and the line sensor was 326 mm. The scanning cycle of the line sensor was 0.5 ms, and the resolution in the flow direction at the outer peripheral portion was 30 μm / pixel.

The signal obtained by the line sensor was processed by the image processing section 16 to detect a defect. The image processing unit 16 is a line image processing device (model name: LSC-
300) and convert the analog video signal of the line sensor to A
After performing / D conversion, binarization, and run-length encoding, the size, position, and the like of the defect were measured. The state of occurrence of the defect was processed by the host computer 17 and displayed on the display 21.

With the apparatus of this embodiment, various kinds of defects such as scratches, dents and defective polishing contained in the disk 10 could be detected stably. In addition, the appearance of the flaw changes depending on the lighting direction, but a total of about 140 degrees (within ± 70 degrees)
Since the light was irradiated from the range, the flaws at various angles could be detected stably.

[0065]

According to the inspection method using the defect inspection apparatus of the present invention, the polishing direction is recognized in advance, the fluctuation of the image data when the polishing direction is changed is suppressed, and the automatic inspection excellent in the defect detection accuracy is performed. be able to. Further, the polishing direction detecting apparatus and method of the present invention can effectively grasp the polishing direction of the disk.

[Brief description of the drawings]

FIG. 1 is a diagram showing a _first emission angle a ₁ and a _first light reception angle b ₁ .

FIG. 2 shows installation positions of a first light emitting unit and a first light receiving unit,
FIG. 4 is a diagram illustrating a relationship between a polishing direction of a disk and a reflection pattern.

FIG. 3 is a diagram showing a relationship between an output angle of a light receiving unit and a horizontal emission angle between a polishing direction of a disc and a light irradiation direction.

FIG. 4 is a diagram schematically illustrating an example of a configuration of an inspection device.
Polishing direction recognition means 7 used in another process in the embodiment
Are also shown for convenience of explanation.

FIG. 5 is a diagram showing a _second emission angle a ₂ and a _second light reception angle b ₂ .

FIG. 6 is a diagram for explaining a second light emitting unit, a light shielding unit, an irradiation range, and the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st disk holding | maintenance part 2 1st light-emitting part 3 1st light receiving part 4 1st moving mechanism 5 polishing direction recognition part 6 reflection pattern 7 polishing direction recognition means 10 disk 11 2nd disk holding part 12th Second light emitting unit 13 Second light receiving unit 14 Second moving mechanism 15 Illumination device 31, 32 Light shielding unit 41-46 Second light emitting unit 51-56 Second light emitting unit 61, 62 Second light receiving Reading position

Claims (7)

[Claims] 1. A first disk holding portion (1), a first light emitting portion (2) for emitting light to a disk surface, and a first light receiving portion (3) for receiving light reflected from the disk surface. And a system including a first light emitting portion (2) and a first light receiving portion (3) such that a horizontal emitting angle between the first emitted light and the polishing direction of the disk continuously changes. A first moving mechanism (4) for changing a relative positional relationship with the disk, a polishing direction recognition unit (5) for recognizing a polishing direction of the disk based on a change in output of the first light receiving unit (3), A disk holding part (11) and one or more second light emitting parts (12), and only light having a horizontal emission angle between the emitted light and the polishing direction within a predetermined range is provided on the disk surface. An illumination device (15) for relatively changing the direction of light irradiation so as to irradiate light onto the disk surface; At least one second light receiving unit (13) that emits light, and a relative position between the second light receiving unit (13) and the disk so that the entire inspection area on the disk surface is scanned by the second light receiving unit (13). A second moving mechanism (14) for changing the physical positional relationship, and the second light receiving unit (1).
3) A disk surface defect inspection apparatus having an image processing section (16) for processing the signal from (3). 2. A point sensor is used as the first light receiving section (3), and a rotating mechanism for rotating the disk around a perpendicular passing through the center of the disk is used as the first moving mechanism (4). The illumination device (15) is moved above two concentric circles centered on two points O ₁ and O ₂ which are points on one diameter of the disk and are the midpoints of the outer and inner diameters of the disk. And a plurality of second light emitting portions (12) installed in the first and second light emitting portions (12), which are rotatable around O ₁ and O ₂ , respectively. A light-shielding portion (31, 32) for shielding light having a direction emission angle outside the predetermined range, and is installed vertically above the diameter and an extension thereof as the second light-receiving portion (13). 2. The method according to claim 1, wherein a line sensor is used. Disk surface defect inspection apparatus. 3. The disk surface defect inspection apparatus according to claim 1, wherein at least one second light receiving section (13) for receiving the reflected light from the disk surface and the second light receiving section (13). Instead of the second light receiving portion (13) and the second moving mechanism (14) for changing the relative positional relationship between the disk so that the entire inspection range on the disk surface is scanned, reflection from the disk surface is performed. A disk surface defect inspection device including a second light receiving unit (13) that receives light and can read the entire inspection range on the disk surface. 4. A polishing direction recognizing means (7) for recognizing a polishing direction of a disk surface, and a second disk holding portion (11).
And one or more second light emitting portions (12), and relatively irradiates the light so that the horizontal emission angle between the emitted light and the polishing direction irradiates only light within a predetermined range. Illumination device that irradiates light to disk surface while changing (15)
And at least one second light receiving unit (13) for receiving light reflected from the disk surface; and the second light receiving unit (13).
A second moving mechanism (for changing the relative positional relationship between the system including the illuminating device (15) and the second light receiving unit (13) and the disk so that the entire inspection range on the disk surface is scanned by the 14) and an image processing unit (16) for processing a signal from the second light receiving unit (13). 5. After recognizing the polishing direction of the disk surface using the apparatus according to claim 1, the illumination device emits light whose horizontal emission angle between the emitted light and the polishing direction is within a predetermined range. A method of inspecting the disk surface for defects by irradiating the disk surface. 6. A first disk holding part (1), at least one first light emitting part (2) for emitting light to a disk surface, and a first light receiving part for receiving light reflected from the disk surface. A first light-receiving section (3) paired with the light-emitting section, and a first light-emitting section (2) and a second light-emitting section (2) such that a horizontal emission angle between the emitted light and the polishing direction of the disc continuously changes. A first moving mechanism (4) for changing a relative positional relationship between a system including one light receiving section (3) and the disk, and recognizing a polishing direction of the disk from a change in output of the first light receiving section (3); And a polishing direction recognition unit (5). 7. A method for recognizing a polishing direction using the apparatus according to claim 6.